Popular Pages

Share

Taurus


Transit Date of principal star:
30 November


Is Taurus attacking Orion, the Hunter, or are the Horns of the Bull the real story?

The horn was a symbol of fertility and bountiful riches in many cultures for thousands of years, and it is probably the case here, for the constellation would have announced the Vernal Equinox at around 4000 BC.

The constellation Taurus may also allude to the Greek story of Europa and the Bull. Europa was daughter of King Agenor. One fine spring day, accompanied by her hand maidens, Princess Europa went to the seashore to gather flowers. Zeus, who had fallen in love with Europa, seized the opportunity.

Zeus transformed himself into a magnificent white bull, and as such he joined King Agenor's grazing herd. Europa noticed the wonderful white beast, who gazed at them all with such a mild manner that they were not frightened.

Europa wove wreathes of flowers for the beast, and wrapped them around his horns. She led him around the meadow, and he was as docile as a lamb. Then, as he trotted down to the seashore, she jumped onto his shoulders. Suddenly, to her surprise and fright, he plunged into the sea and carried the princess to Crete.

As they reached the Cretan shore, Zeus then turned into an eagle and ravaged Europa. She bore three sons, the first of which was Minos.

Minos is said to have introduced the bull cult to the Cretans. He had Daedalus build a labyrinth in the depths of his palace at Knossus, which became the home of the Minotaur (offspring of Mino's wife Pasiphae, and a bull). Seven young men and seven maidens were ritually sacrificed to the Minotaur until Theseus killed it.

Minos, in fact, was the title of the ancient rulers of Crete, and the story probably tells of their mythic origin.


The constellation shows mainly the horns, and exceedingly long horns they are. The left (southern) horn starts from the group of stars known as The Hyades, of which Aldebaran seems (erroneously) to be a member. It extends from Aldebaran to zeta Tauri, near the eastern edge of the constellation.

The right horn lifts up just west of the Hyades, from delta Tauri through tau Tauri and finally to its tip at beta Tauri (El Nath: remember this star as part of Auriga?)

The rest of the bull is rather disappointing; a slight body and two spindly legs. It may be that the bull is half-emerged in water, as it carries Europa across to Crete.


The stars of Taurus:

Taurus' eye is bright and piercing. This is Aldebaran (alpha Tauri), an orange giant about 40 times the size of the Sun. Aldebaran is an old star. For billions of years it has burned its supply of hydrogen until there is little left. Its future won't be as a spectacular explosion of a supernova but rather a gradual dimming into a white dwarf.

Following the lower horn out to its tip we find zeta Tauri. This is a shell star. Shell stars are main-sequence stars which rotate rapidly, causing a loss of matter to an ever-expanding shell.

Most of the interesting features of Taurus are found in the centre of the constellation and toward the west. Around Aldebaran are a number of stars which go by the collective name of The Hyades (see below).

Aldebaran is not a member of this group. Not only is it closer to us, but its proper motion is at a different angle. Aldebaran is moving at an angle of 161 degrees, the stars of the Hyades at around 102-109 degrees.


Double stars in Taurus

[NOTE: See the Binocular Section link, at the bottom of this page, for updated values.]

Taurus has an abundant selection of binary stars, including many Struve binaries that we haven't mentioned. Below is a very small selection of some of the easier doubles to resolve.

Theta2 and theta1 form a fixed binary of wide separation, theta2 just below and to the east. Note that theta2 is the primary: 3.4, 3.8; PA 346 and separation 337".

Kappa1 and kappa1 form an easily resolved binary: 4.2, 5.3; PA 328, separation 5.3".

Sigma2 and sigma1 is another wide fixed binary. And again, sigma2 is the primary: 4.8, 5.2; PA 193 and separation 431".

80 Tauri is a difficult visual binary with an orbit of 189.5 years: 5.5, 8.0; current PA 17 and separation of 1.8" (very nearly its maximum separation).

Struve 422 is a wide visual binary with an orbit of over 2000 years: 5.9, 8.8; PA 269, 6.7". It's located at 9 SW of nu Tauri, just north of the brighter 10 Tauri.


Variable Stars in Taurus:

Many of the more notable variable stars in Taurus are of a type not noticed by casual observation, such as alpha Taurus, which is classified as an Lb type variable. These are irregular giants whose variation can only be detected by means of photoelectric photometry. Alpha Taurus only changes in visual magnitude by 0.2, from 0.75 to 0.95, and the period is irregular.

BU Tauri (Pleione) is a gammaCas type variable, from 4.77 to 5.50. GammaCas variables are also characterised by an irregular period, which may sometimes be very rapid. These are B stars, quite young, and rotate very rapidly. This rotation results in the throwing off of material, which then forms a shell around the star. The cause of its variation is still not understood.

Zeta Tauri is also a gammaCas type variable, with a variation from 2.88 down to 3.17 roughly every 133 days.

Lambda Tauri, in the Hyades cluster, is a good example of an eclipsing variable. The variability is caused by the partial eclipse of the primary by its companion, dimming the 3.3 visual magnitude down to 3.8 every 3.95 days.

R Tauri is a Mira-type variable with a 320.9 day period. Usually at 7.6, it drops to a very dim 15.8 once a year. In 2000 the maximum should occur in the first week of May.


Deep Sky Objects in Taurus:

Taurus contains two well known Messier objects: the Crab Nebula and the Pleiades. Besides these two there is the `other' cluster, known as The Hyades, and the curious "Hind's Variable Nebula".

Just northwest of zeta Tauri is the first of Messier's objects: M1, the Crab Nebula. Early observers thought the object to be a star cluster, something like a dimmer version of the Great Orion Nebula. Messier was so intrigued by it, on the night of 12 September, 1758, that he began his catalogue - the purpose of which was to keep observers from mistaking such objects for comets.

It takes a rather large telescope to see any of the filamentary features of the nebula; most viewers come away disappointed.

The Crab Nebula is a remnant of a supernova, whose explosion occurred (or rather, was visibly recorded) in July of 1054. Chinese and Japanese astronomers witnessed the event. In fact, it would have been difficult not to notice, for the night sky would have been lit up by a star with the visual magnitude of about -5, bright enough to be seen even in the daytime for nearly a month.

The star that exploded, producing the nebula, is now an optical pulsar. Even now, nearly a thousand years later, the nebula is hurtling through space at roughly a thousand kilometers per second. And it continues to grow; the nebula is now over thirteen light years in diameter (four parsecs) according to the Facts On File Dictionary of Astronomy.

M45, The Pleiades.

This open cluster contains as many as three thousand stars. The brightest seven go under the name The Seven Sisters" (from brighter to dimmer): Alcyone (eta Tauri), Electra, Maia, Merope, Taygeta, Celaeno, and Asterope. Added to the list are also Pleione (BU Tauri = 28 Tauri), just east of Alcyone, and Atlas (27 Tauri) who are actually Mum and Dad for the seven sisters. (The two are often seen as one star; it takes a clear night to see them as two separate stars.)

The Hyades

This open cluster of about two hundred stars is only 150 light years away, and considered to be about 600 million years old. It is shaped like a "V", just to the west of Aldebaran.

Just as the Pleiades have individual names, so did the Hyades at one time. In fact, these stars were supposed to be the half-sisters of the Pleiades, and Robert Burnham (Celestial Handbook) gives their names - and a great deal more on this group. Theta2 is the brightest star of the group, which forms a binary with theta1 (see below). The group is thought to be about 400 million years old.

These nine stars, then, constitute the minimum count, easily seen with the naked eye, while there are actually as many as 250 stars which belong to the group. The cluster is estimated to be 415 light years away. Even a small telescope brings this famous star cluster alive.

Hind's Variable Nebula
(NGC 1555)

This curious deep sky object is located two degrees west of epsilon Tauri, and two degrees north of delta Tauri. First look for the rather dim variable T Tauri. Burnham (Celestial Handbook) has a finder's chart, on page 1833. The star has an irregular variability, from 9 to 13.

Very close to T Tauri, just off to the west, is a cloud-like object. This is Hind's Variable Nebula. Its variability is long-lasting; from 1869 to 1890 it couldn't be found at all. Presently, it seems to be gaining slightly in visual magnitude, although its actual visual magnitude hasn't been determined.


For a more detailed appreciation of Taurus visit the Binocular Section.


Return to the previous page:

Or go to

the Main Menu


All files associated with The Constellations Web Page are
Richard Dibon-Smith.